The Jefferson Island dome is the location of Lake Peigneur, which grew substantially during a 1980 incident where an underground salt mine, active at the time, was accidentally drilled into by a floating drill rig on the lake. The lake drained quickly into the excavated mining corridors underground, pulling the rig and boats along with it. Air and water, pushed out of other mine entrances on land, blew upwards in plumes. Once it stabilized, the lake, much bigger now, had washed away several shoreline structures, and the salt mine, now flooded, was closed. Two underground gas storage cavities, with around 3 million barrels capacity, are still in use.
